#25774 closed New feature (fixed)
Refactor of datetime expressions and better, official support for right-hand-side date part extraction
Reported by: | David Filipovic | Owned by: | Josh Smeaton |
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Component: | Database layer (models, ORM) | Version: | dev |
Severity: | Normal | Keywords: | db, expressions, date, time, extract, transform 1.10 |
Cc: | josh.smeaton@…, info+coding@…, aksheshdoshi@… | Triage Stage: | Ready for checkin |
Has patch: | yes | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description (last modified by )
As previously stated in this ticket and this thread, I have begun work on the following:
- making the so called datetime transforms (currently residing in
django.db.models.lookups
) part of the officially supported ORM API as part of the db expressions, - making these transforms easily usable on the right hand side of lookups / Q objects
To this effect, I propose the following:
- replace module
django.db.models.expressions
with a package of the same name - add module
django.db.models.expressions.datetimes
- rename
XTransform
toXExtract
and move them fromdjango.db.models.lookups
todjango.db.models.lookups
todjango.db.models.expressions.datetimes
- change
YearLookup
andYearComparisonLookup
to allow for functions on the right hand side
- extensive testing of these db expressions
- adding this to the release notes
- any other change that might support this
I'm also adding a PR with some of these already implemented. What remains to be done is:
- replace references
XTransform
type classes indjango.db.models.lookups
withXExtract
classes fromdjango.db.models.expressions.datetimes
- replace these references anywhere else in the project (I've noticed there are some in the tests, for instance)
With the API in the PR it becomes possible to do the following lookup:
from django.db.models.expressions.datetimes import DateExtract Person.objects.filter(birth_date__year=DateExtract('job__start_date', lookup_name='year'))
which is equivalent to:
from django.db.models.expressions.datetimes import YearExtract Person.objects.filter(birth_date__year=YearExtract('job__start_date'))
Additionally, @jarshwah suggested that these should maybe be named: ExtractX
instead of XExtract
.
Change History (19)
comment:1 by , 9 years ago
Description: | modified (diff) |
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Needs documentation: | set |
Needs tests: | set |
comment:2 by , 9 years ago
Triage Stage: | Unreviewed → Accepted |
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comment:3 by , 9 years ago
Josh, I've actually tweaked YearLookup
and YearComparisonLookup
already.
I've reversed the order of process_lhs
and process_rhs
to make process_rhs
occur first, and then based on the result of that processing, specifically, based on whether there are any rhs_params
returned, the lhs processing branches to accommodate right hand side based on both a parameter and a function.
comment:4 by , 9 years ago
Cc: | added |
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comment:5 by , 9 years ago
Owner: | changed from | to
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Status: | new → assigned |
Since David appears to have left this ticket I'll pick this up. Initial patch: https://github.com/django/django/pull/6243
comment:6 by , 9 years ago
Needs documentation: | unset |
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Needs tests: | unset |
Triage Stage: | Accepted → Ready for checkin |
Patch is ready for review.
comment:7 by , 9 years ago
Triage Stage: | Ready for checkin → Accepted |
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The review queue is "Accepted + Has patch".
comment:8 by , 9 years ago
Cc: | added |
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comment:9 by , 9 years ago
Patch needs improvement: | set |
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comment:10 by , 8 years ago
Patch needs improvement: | unset |
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comment:11 by , 8 years ago
Keywords: | 1.10 added |
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Patch needs improvement: | set |
Left comments for improvement on the PR.
comment:12 by , 8 years ago
Patch needs improvement: | unset |
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Triage Stage: | Accepted → Ready for checkin |
Ready for merge unless feature required for timezone support requiring pytz as mentioned https://github.com/django/django/pull/6243#issuecomment-219282120
comment:13 by , 8 years ago
Triage Stage: | Ready for checkin → Accepted |
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I added another commit to provide tzinfo support for Extract subclasses. New commit is: https://github.com/django/django/pull/6243/commits/4f08553fb0431184fdcc3e0eb9c3c52fa2bba09e
comment:14 by , 8 years ago
Triage Stage: | Accepted → Ready for checkin |
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I think you're on the right track for most of these points. I'm not yet convinced that adding
DateExtract
is necessary, but once the patch is written I'll take another look then. I just worry that there'll be two ways to extract a date part and that may lead to confusion.Would like others opinions on ExtractX rather than XExtract. I think it reads and sorts better.
YearLookup and YearComparisonLookup are going to be interesting. They'll still need to work the same way when used on the left hand side. Perhaps we can rename to YearLookupOptimised (for example, that's a bad name) and register that as a lookup, but provide a different ExtractYear that does what you'd expect on the right hand side. The optimised version would then just be a hidden implementation detail that users shouldn't touch themselves.
I'll have a look at the actual PR tomorrow. Great work so far.